我在Ruby中有一个元素数组
[2,4,6,3,8]
例如,我需要删除值为3的元素
我怎么做呢?
我在Ruby中有一个元素数组
[2,4,6,3,8]
例如,我需要删除值为3的元素
我怎么做呢?
当前回答
我改进了尼尔斯的解决方案
class Array
def except(*values)
self - values
end
end
现在你可以使用
[1, 2, 3, 4].except(3, 4) # return [1, 2]
[1, 2, 3, 4].except(4) # return [1, 2, 3]
其他回答
以下是一些基准:
require 'fruity'
class Array
def rodrigo_except(*values)
self - values
end
def niels_except value
value = value.kind_of?(Array) ? value : [value]
self - value
end
end
ARY = [2,4,6,3,8]
compare do
soziev { a = ARY.dup; a.delete(3); a }
steve { a = ARY.dup; a -= [3]; a }
barlop { a = ARY.dup; a.delete_if{ |i| i == 3 }; a }
rodrigo { a = ARY.dup; a.rodrigo_except(3); }
niels { a = ARY.dup; a.niels_except(3); }
end
# >> Running each test 4096 times. Test will take about 2 seconds.
# >> soziev is similar to barlop
# >> barlop is faster than steve by 2x ± 1.0
# >> steve is faster than rodrigo by 4x ± 1.0
# >> rodrigo is similar to niels
再次使用包含大量重复项的更大数组:
class Array
def rodrigo_except(*values)
self - values
end
def niels_except value
value = value.kind_of?(Array) ? value : [value]
self - value
end
end
ARY = [2,4,6,3,8] * 1000
compare do
soziev { a = ARY.dup; a.delete(3); a }
steve { a = ARY.dup; a -= [3]; a }
barlop { a = ARY.dup; a.delete_if{ |i| i == 3 }; a }
rodrigo { a = ARY.dup; a.rodrigo_except(3); }
niels { a = ARY.dup; a.niels_except(3); }
end
# >> Running each test 16 times. Test will take about 1 second.
# >> steve is faster than soziev by 30.000000000000004% ± 10.0%
# >> soziev is faster than barlop by 50.0% ± 10.0%
# >> barlop is faster than rodrigo by 3x ± 0.1
# >> rodrigo is similar to niels
甚至更大,有更多的副本:
class Array
def rodrigo_except(*values)
self - values
end
def niels_except value
value = value.kind_of?(Array) ? value : [value]
self - value
end
end
ARY = [2,4,6,3,8] * 100_000
compare do
soziev { a = ARY.dup; a.delete(3); a }
steve { a = ARY.dup; a -= [3]; a }
barlop { a = ARY.dup; a.delete_if{ |i| i == 3 }; a }
rodrigo { a = ARY.dup; a.rodrigo_except(3); }
niels { a = ARY.dup; a.niels_except(3); }
end
# >> Running each test once. Test will take about 6 seconds.
# >> steve is similar to soziev
# >> soziev is faster than barlop by 2x ± 0.1
# >> barlop is faster than niels by 3x ± 1.0
# >> niels is similar to rodrigo
我喜欢在其他答案中提到的-=[4]方式来删除值为4的元素。
但有这样一种方法:
[2,4,6,3,8,6].delete_if { |i| i == 6 }
=> [2, 4, 3, 8]
在“基本数组操作”中提到的map函数之后。
在ruby中编译所有不同的delete选项
delete -按值删除匹配的元素。如果有多个值匹配,则删除所有值。如果您不关心出现的次数或确定单个出现,则使用此方法。
a = [2, 6, 3, 5, 3, 7]
a.delete(3) # returns 3
puts a # return [2, 6, 5, 7]
delete_at -删除给定索引处的元素。如果你知道索引,就用这个方法。
# continuing from the above example
a.delete_at(2) # returns 5
puts a # returns [2, 6, 7]
delete_if -删除block为true的每个元素。这将修改数组。数组在调用块时立即改变。
b = [1, 2, 5, 4, 9, 10, 11]
b.delete_if {|n| n >= 10}. # returns [1, 2, 5, 4, 9]
reject -该函数将返回包含给定块为false的元素的新数组。顺序是用这个来维持的。
c = [1, 2, 5, 4, 9, 10, 11]
c.reject {|n| n >= 10}. # returns [1, 2, 5, 4, 9]
拒绝!-同delete_if。数组在调用块时可能不会立即改变。 如果你想从数组中删除多个值,最好的选择如下所示。
a = [2, 3, 7, 4, 6, 21, 13]
b = [7, 21]
a = a - b # a - [2, 3, 4, 6, 13]
借用Travis的评论,这是一个更好的答案:
我个人喜欢[1,2,7,4,5]-[7],结果=>[1,2,4,5]从irb
我修改了他的答案,因为3是他示例数组中的第三个元素。对于那些没有意识到3在数组中的位置2的人来说,这可能会导致一些困惑。
另一个选择:
a = [2,4,6,3,8]
a -= [3]
结果是
=> [2, 4, 6, 8]